1. Technical Field
The present invention relates to a method of manufacturing a light guide panel, and more particularly to a method of manufacturing a mold for the light guide panel of a backlight unit and a method of manufacturing a light guide panel.
2. Description of the Related Art
Liquid crystal displays (LCDs) are light-receiving-type flat panel display devices. Since LCDs do not emit light themselves, they use light from the outside to display the desired image. The light for image display is often provided by a backlight unit that is installed behind the LCD to emit light.
Backlight units are classified into a direct-light type backlight unit and an edge-light type backlight unit depending on the arrangement form of light sources. According to the edge-light type backlight unit, light is emitted from a light source installed along an edge of a light guide panel, which installed under a liquid crystal display panel. The emitted light is transmitted to the liquid crystal display panel through the light guide panel. The light guide panel converts the light from the light source into a surface light and emits it in a vertical direction. To help this conversion, a scattering pattern or hologram pattern for efficiently converting the light from the light source into the surface light may be formed on the light guide panel.
A line light source and a point light source can be used as the light source in the edge-light type backlight unit. Light emitting diodes (LEDs) are popular choices as a light source in a display device when slimness and light weight are important characteristics.
Consumer demands for improved optical characteristics such as luminance, uniformity and color sensitivity (among other characteristics) in backlight units are continuously increasing. Of the different optical characteristics, luminance and uniformity depend a lot on functional sheets and a light guide panel. In order to improve luminance and remove dark portions, a prism pattern is formed on light-receiving portions of the light guide panel on which light from a light source is incident.
In order to form such a prism pattern, a fine prism pattern is processed on a side mold for the light guide panel. Processing methods such as V-cutting, grinding, electric discharge machining, wire electric discharge machining, and milling may be used in forming the fine prism pattern. Shape or surface accuracy of the prism pattern directly affects the optical characteristics of the light guide panel since the prism pattern contacts the adjacent LED. However, the aforementioned processing methods cannot produce the desired shape or surface accuracy.
Recently, an ultra-precision micromachining technology has been developed that uses a MEMS (Micro Electro Mechanical System) technology. This ultra-precision micromachining technology bombines the MEMS technology with an optical lithography technology, so that an accuracy grade of the ultra-precision micromachining technology is increased to a nano-order level. However, since such a technology is mainly applied to a polymer based resin, it is difficult to directly apply the technology to prism pattern processing of the light-receiving portions of the light guide panel.